RECOMMENDATION ITU-R SF.1602 - Methodology …...Recommendation ITU-R SF.1602 (02/2003) Methodology for determining power flux-density statistics for use in sharing studies between

Recommendation ITU-R SF.1602 (02/2003)

Methodology for determining power flux-density statistics for use in sharing studies

between fixed wireless systems and multiple fixed-satellite service satellites

SF Series

Frequency sharing and coordination between

fixed-satellite and fixed service systems

ii Rec. ITU-R SF.1602

Foreword

The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the

radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without

limit of frequency range on the basis of which Recommendations are adopted.

The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional

Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups.

Policy on Intellectual Property Right (IPR)

ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of

Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent

holders are available from http://www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the

Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found.

Series of ITU-R Recommendations

(Also available online at http://www.itu.int/publ/R-REC/en)

Series Title

BO Satellite delivery

BR Recording for production, archival and play-out; film for television

BS Broadcasting service (sound)

BT Broadcasting service (television)

F Fixed service

M Mobile, radiodetermination, amateur and related satellite services

P Radiowave propagation

RA Radio astronomy

RS Remote sensing systems

S Fixed-satellite service

SA Space applications and meteorology

SF Frequency sharing and coordination between fixed-satellite and fixed service systems

SM Spectrum management

SNG Satellite news gathering

TF Time signals and frequency standards emissions

V Vocabulary and related subjects

Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1.

Electronic Publication

Geneva, 2011

ITU 2011

All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU.

http://www.itu.int/ITU-R/go/patents/en

http://www.itu.int/publ/R-REC/en

Rec. ITUR SF.1602 1

RECOMMENDATION ITU-R SF.1602

Methodology for determining power flux-density statistics for use

in sharing studies between fixed wireless systems

and multiple fixed-satellite service satellites

(2003)

Scope

At some elevation angles on the surface of the Earth, the power flux-density produced by a satellite may be

smaller than the limiting values required by conformance to a given pfd mask because of the limitations of

real antenna gain patterns and the need to avoid self interference. This Recommendation provides a

methodology for determining the statistics of the power flux-density produced at the surface of the Earth by

satellites in GSO or non-GSO orbits.

The ITU Radiocommunication Assembly,

considering

a) that it is necessary to ensure that emissions from satellites do not exceed permissible

interference to fixed wireless systems (FWS) in the bands shared between FS and FSS;

b) that FWS can be adequately protected from the aggregate emissions from multiple satellites

(non-GSO constellations or fully populated GSO arc) by placing suitable limits on the power flux-

density (pfd) in a reference bandwidth produced by individual satellites at the surface of the Earth;

c) that any limitations of the pfd produced at the surface of the Earth should not place undue

restrictions on the design of GSO and non-GSO FSS;

d) that Recommendations ITU-R SF.1482 and ITU-R SF.1483 provide maximum allowable

values of pfd at the surface of the Earth produced by non-GSO satellites in the FSS to protect the FS

in, respectively, the 10.7-12.75 GHz and the 17.7-19.3 GHz bands;

e) that the pfd levels specified in the Recommendations mentioned in considering d) were

developed from a pfd mask analysis used to calculate the statistics of aggregate power levels

received at an FS station by applying pfd levels under consideration to each visible satellite of the

non-GSO FSS constellation;

f) that, when considering a multi-satellite environment, such as non-GSO constellation or

fully populated GSO arc, all the visible satellites may not simultaneously radiate the maximum pfd

limit in the direction of the FS system under consideration,

recommends

1 that the methodology described in Annex 1 may be used for determining pfd statistics for

use in sharing studies between FWS and multiple FSS satellites, taking into account satellite

systems characteristics.

Radiocommunication Study Groups 5 and 4 made editorial amendments to this Recommendation in

November 2010 and September 2011, respectively, in accordance with Resolution ITU-R 1.

2 Rec. ITU-R SF.1602

Annex 1

Methodology for determining pfd statistics for use in sharing studies between

fixed wireless systems and multiple FSS satellites

1 Introduction

This Annex presents statistical methodology concerning the impact of non-GSO and GSO satellites

on FWS. It takes into account realistic satellite characteristics and is intended for use as guidance in

sharing analysis between FS and satellite services.

It should also be noted that Recommendations ITU-R SF.1482 and ITU-R SF.1483 dealing with

maximum allowable values of pfd at the surface of the Earth produced by non-GSO satellites in the

FSS to protect the FS provides general background to this methodology.

2 Description of the pfd mask analysis

The existing methodology for evaluating the pfd mask used either for GSO or non-GSO satellite

systems, such as in the above-mentioned Recommendations ITU-R SF.1482 and ITU-R SF.1483,

aggregates the interference from all visible satellites to the FS using a regulatory pfd mask such as

defined in Article 21 of the Radio Regulations.

In a typical application of this methodology for the case of GSO satellites, the geostationary arc is

filled with a given number of satellites (e.g. 1 every 4°) which produces permanent interference.

Representative results produced by the application of this methodology are shown on Fig. 1 for all

the FS azimuths.

1602-01

0 50 100 150 200 250 300 35025 75 125 175 225 275 325

21

16

11

6

1

–4

–9

–14

–19

–24

FIGURE 1

Interference produced by a GSO satellite

FS azimuth (degrees)

20° elevation

10° elevation

I/N

(d

B)

Rec. ITUR SF.1602 3

For the case of non-GSO systems, and on the basis of the characteristics of each single constellation

(number of satellites, number of planes, inclination(s), altitude, ...), the statistics of the theoretical

aggregate power levels received at an FS station are calculated by applying pfd limits under

consideration to each visible satellite of the non-GSO FSS constellation (see Recommendation

ITU-R F.1108). In a typical application of this methodology, the interference distribution is

calculated for the FS azimuth (and for a single elevation angle) that represents the constellation

worst-case, which results in distribution of interference level versus percentage of time such as

given in Fig. 2.

This methodology has typically been used as a basis in inter-service sharing studies. This has the

advantage of being a simple calculation but also represents an overestimation of the real

interference that could be suffered by FS stations.

With regard to the FSS characteristics, the analysis assumes that all the visible satellites radiate

simultaneously at the maximum pfd limits, in the direction of the FS system under consideration.

Such an assumption does not take into account the patterns of the real satellite antenna, the power

limitations of each satellite or the restrictions that self-interference (as a result of frequency reuse)

would impose on an FSS system as well as the fundamental operational constraints of FSS systems.

The methodology described in § 3 provides a statistical approach toward accommodating the FSS

operational characteristics.

3 pfd analysis and satellite models

This methodology takes into account realistic satellite antenna patterns, the power limitations of

each satellite and the restrictions that self-interference would impose on a non-GSO FSS system, as

well as the fundamental operational constraints of non-GSO FSS systems.

This methodology assumes that, in a multi-satellite environment, all the satellites visible from a

given point on the Earth do not simultaneously produce the maximum pfd allowed by a mask.

The parameters necessary to accurately model the pfd produced by a given satellite (maximum

power, number of beams, antenna gain and antenna pattern) can generally be found in ITU-R

documentation. The following is an analytical model of some of the possible parameters of a GSO

FSS and a non-GSO FSS system.

1602-02

–55 –50 –45 –40 –35 –30 –25 –20 –15 –10 –5 50 1510 20

100

10

1

10–1

10–2

FIGURE 2

Interference distribution produced by a non-GSO system

I/N (dB)

Per

cen

t o

f o

ccu

ren

ce

20° elevation

10° elevation


The values of such parameters depend on the considered frequency band and the type of satellite

(GSO or non-GSO). It is possible to derive a general equation linking them together.

In the main beam, for single beam coverage satellites, which could be implemented in certain

frequency bands, the radiated power of the satellite necessary to produce the maximum pfd in the

main beam is:

)4log(10 2dGpfdP sms (1)

where:

Ps : power density of the satellite (dB(W/MHz))

pfdm : the maximum value of the pfd mask

Gs : antenna gain of the satellite (dBi)

d : range from the satellite to its sub-satellite point (m).

However, in high frequency bands such as the 20/30 GHz or 40/50 GHz bands, most satellites will

more likely deploy multiple beams with higher antenna gain, transmitting on several channels. In

this case, the power density of each individual beam can be calculated as:

tot

tot

tot

tot

f

fds

BWN

P

N

BW

NN

P

BW

PP log10log10log10 (2)

where:

Pds : satellite power density per beam (dB(W/MHz))

Pf : power per beam (W)

BWf : beam bandwidth (MHz)

Ptot : total radiated power available on the satellite (W)

BWtot : total bandwidth of the satellite (MHz)

N : number of frequency channels in BWtot

N : number of co-frequency beams.

On this basis, equations (1) and (2) allow to derive the following general equation:

)π4log(10log10 2dBWN

PpfdG

tot

totmb

which gives:

)π4log(10)log(10)log(10)log(10 2dBWNPpfdG tottotmb (3)

where:

Gb : beam antenna gain (dBi)

pfdm : the maximum value of the pfd mask (dB(W/(m2 · MHz)))

Ptot : total radiated power available on the satellite (W)

N : number of co-frequency beams

Rec. ITUR SF.1602 5

BWtot : total bandwidth of the satellite (MHz)

d : distance from the satellite to the centre of its pointing zone (m).

Therefore, based on this equation (3) and using existing typical values that can generally be found

in ITU-R texts, it is possible to define simple satellite models which could be used in sharing

studies between FSS and terrestrial services.

As an example, and in order to facilitate the understanding of and support the statistical

methodology presented in this Annex, example satellite models below, assumed to be consistent

with equation (3) (with a –105 dB(W/(m2 · MHz)) high elevation angle pfd level), have been

considered:

GSO satellites:

Model GEO1:

beam antenna gain: 60 dBi

number of co-frequency beams: 6

total transmit power (for all beams): 3.5 kW

total bandwidth: about 1 000 MHz

Model GEO2:




total bandwidth: about 500 MHz

Non-GSO satellites (10 000 km altitude assumed):

Model MEO1:





Model MEO2:





4 pfd distribution

4.1 Principles

As already stated above, the pfd produced by a given satellite, at any point on the surface of the

Earth, depends on its transmitted power, antenna gain and antenna pattern.

Furthermore, as shown in Fig. 3, the maximum pfd available in the main beam is mainly controlled

by the regulatory pfd limit and the antenna pattern. In many cases, depending on the pointing

elevation of the satellite, the pfd in the main beam is lower than the one given by the pfd mask in

order to stay within the mask for lower elevation (such as for Elevations a and c in Fig. 3).


Furthermore, as described in Figs. 4 and 5, a satellite seen from a given point A on the Earth with

an Elevation x, does not generally produce a constant pfd at A. The received pfd level at A varies

based on the satellite downlink beam pointing direction and may also vary based upon traffic load.

However, this latter characteristic is not taken into account in this methodology.

1602-03

FIGURE 3

Elevation a

Elevation c

Elevation b

Main beam

direction

0° elevation

1602-04

A

FIGURE 4

Sub-satellite point

Main beam direction

Elevation x

Rec. ITUR SF.1602 7

In Fig. 4, it can be seen that the pointing direction of the satellite beam is close to point A and that

the antenna discrimination angle, , is relatively small. On the other hand, in Fig. 5, the pointing

direction of the satellite beam is different and the antenna discrimination angle, , is bigger

than . Furthermore, and as explained above, the pfd in the main beam for these two examples can

be different.

Therefore, the pfd produced at point A can be different even though the satellite is at exactly the

same position.

The pfd radiated in A can be easily calculated as follows:

AdiscrimaxmbmbA LGGLpfdpfd (4)

where:

pfdA : pfd radiated in A (dB(W/MHz))

pfdmb : pfd radiated in the main beam (dB(W/MHz))

Lmb : free space losses between the satellite and the centre of its beam at the Earth's

surface (dB)

Gmax : maximum satellite antenna gain (dBi)

Gdiscri : relative antenna gain in the direction of point A (dBi)

LA : free space losses between the satellite and A (dB).

On this basis, and by varying the pointing direction of the satellite in all possible directions from its

position, it is possible to determine the distribution of the pfd values that a satellite can produce for

a given elevation as described in Fig. 6.

1602-05

A

'

FIGURE 5

Sub-satellite point

Main beam direction

Elevation x


In addition, considering all the elevation angles for a given case (see calculation in Appendix 1), it

is possible to draw the worst-case pfd mask by combining the maximum from each distribution and

to compare it, such as on Fig. 7, with the regulatory pfd mask.

It is also possible, such as on Fig. 7, to plot a similar combined pfd mask representing a given

percentage (e.g. 99.9% and 99.5% of the cases).

1602-06

0

–10

–100

10

100

1 000

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

FIGURE 6

pfd distributions at 30° elevation for GEO1 model (60 dBi multibeam)

pfd levels (dB(W/(m2 · MHz)))

Per

cen

t o

f o

ccu

ren

ce

1602-07

0 10 20 30 40 50 60 70 80 90

–104

–107

–110

–113

–116

–119

–122

–125

–128

–131

–134

–137

–140

–143

FIGURE 7

Aggregate pfd masks for GEO1 model (60 dBi multibeam)

Elevation angle (degrees)

pfd

lev

el

(dB

(W/(

m 2

· M

Hz))

)

Regulatory mask

Maximum

99.9%

99.5%

Rec. ITUR SF.1602 9

4.2 Antenna models

4.2.1 Single beam satellite models

For a single beam satellite, Figs. 4 and 5 give an adequate representation of the situation, but the

resulting pfd depends on the assumed antenna pattern.

Recommendation ITU-R S.672 provides satellite antenna radiation pattern for use as a design

objective in the fixed-satellite service employing geostationary satellites. For non-GSO satellites,

there is no such general Recommendation, but Recommendation ITU-R S.1528 provides patterns

for non-GSO satellites below 30 GHz and guidance for the bands above 30 GHz.

It has to be noted that the single beam satellite model may not be appropriate for use in all

frequency bands.

4.2.2 Multibeam satellite models

For multibeam satellite models such as the GEO or MEO models described in § 3, the

representation of the situation is different since in this case the aggregate impact of all the antennas

has to be taken into account, as shown on Fig. 8.

The pfd value at point A is the aggregation of the pfd produced by each single beam antenna in the

direction of point A, each with a specific antenna discrimination (,or in the above example).

Based on the regulatory pfd mask, this pfd radiated to A can be calculated as follows:

)(

1

N

j

Adiscrijmaxmbjmbj LGGLpfdpfdA (5)

1602-08

'

A

''

FIGURE 8

Sub-satellite point

Main beam direction

Elevation x


where:

pfdA : pfd radiated to A (dB(W/(m2 · MHz)))

N : number of co-frequency beams per satellite

pfdmbj : pfd radiated in the main beam j (dB(W/(m2 · MHz)))

Lmbj : free space losses between the satellite and the centre of the spot beam j at the

Earth’s surface (dB)

Gmax : maximum satellite antenna gain (dBi)

Gdiscrij : relative antenna gain in the direction of point A for the beam j (dBi)

LA : free space losses between the satellite and A (dB).

Since these beams are assumed to be co-frequency and due to self-interference issues, their main

beams will not cover the same zone at the same time.

Therefore, except in some cases where (for which none of the main beams covers point A) for

which the aggregate pfd is only produced by far side lobes of all the beams, this aggregate pfd will

be dominated by one beam at each time.

Instead of running complicated calculations involving multibeams scenarios, the pfd at A can hence

be approximated considering one single beam as follows:

AdiscrijmaxmbmbA LGGLpfdpfd (6)

where:

pfdA : pfd radiated in A (dB(W/(m2 · MHz)))

pfdmb : pfd radiated in the main beam (dB(W/(m2 · MHz)))

Lmb : free space losses between the satellite and the centre of the spot beam j at the

Earth’s surface (dB)

maxG : maximum satellite aggregate antenna gain (dBi)

iscrijdG : relative aggregate antenna gain in the direction of point A for the beam j (dBi)

LA : free space losses between the satellite and A (dB)

and where the aggregate antenna pattern G represents the pattern of one single antenna, G, plus the

effect of the off-axis gain, Goffaxis, of the N other satellite antennas. It is defined as follows:

1010 1010log10

offaxisGG

NG (7)

As an example, and assuming a 0 dBi off-axis antenna gain, the resulting antenna pattern used for

the multibeam models GEO1 (antenna gain 60 dBi) or MEO2 (antenna gain 45 dBi) satellites are

described in Figs. 9a and 9b.

Rec. ITUR SF.1602 11

Finally, once the pfd distribution such as the one given in Fig. 6 is calculated for one beam on the

basis of the aggregate antenna pattern, the pfd distribution for the N beams of the satellite can be

derived as follows:

Npp )1(1 (8)

where:

p : probability of a pfd level radiated in A for one beam

p : probability of a pfd level radiated in A for all the beams

N : number of co-frequency beams per satellite.

1602-09a

0 3 6 9 12 15 18

70

60

50

40

30

20

10

0

Aggregate antenna pattern (6 beams)

Single antenna pattern (Recommendation ITU-R S.672)

Off-axis angle (degrees)

Gain

(dB

i)

FIGURE 9a

GEO 60 dBi antenna (Ls = 30)

0.75 1.5 2.25 3.75 4.5 5.25 6.75 7.5 8.25 9.75 11.25 12.75 13.5 14.25 15.75 16.5 17.2510.5

1602-09b

0 3 6 9 12 15 18

20

15

10

5

0

30

25

40

35

50

45

Aggregate antenna pattern (3 beams)

Single antenna pattern (Recommendation ITU-R S.672)

Off-axis angle (degrees)

Gain

(dB

i)

FIGURE 9b

MEO 45 dBi antenna (Ls = 30)

0.75 1.5 2.25 3.75 4.5 5.25 6.75 7.5 8.25 9.75 10.5 11.25 12.75 13.5 14.25 15.75 17.2516.5


NOTE 1 – Equation (8) is generally used for independent events which, however, is not the case for the

N aggregate antenna patterns. In this example, the dependency of these beams is taken into account by the

use of an aggregate antenna pattern as expressed in equations (6) and (7). Other dependency models may be

applied to this methodology.

On this basis, Fig. 10 describes the pfd distribution calculated for a single beam (using aggregate

antenna pattern) and one calculated for multibeams using equation (8), achieved by varying the

pointing direction of the satellite beams in all possible directions.

4.3 Minimum pointing elevation angle

Depending on the considered frequency band, the attenuation due to rain or other technical

constraints can have an impact on satellite design which may lead to systems not designed for low

elevation angles.

The minimum elevation angle has a significant impact on the sharing conditions between FSS and

FS since all FS stations pointing to a satellite with an elevation lower than the satellite minimum

operational elevation will not suffer main beam to main beam interference.

As an example, Fig. 11 provides a comparison of two pfd distributions, one taking into account a

15° operational elevation limitation for the GSO FSS satellite and the second without elevation

limitation. This Figure shows a difference of more than 15 dB on the maximum pfd value that

confirms the impact of the minimum operational elevation angle.

4.4 Further considerations

The analysis in the previous sections assumes a uniform distribution of the satellite beam

orientation. In practice and depending on the frequency band and applications, the satellites would

tend to orient their beams toward landmasses and in particular population centres. Similarly,

depending on the frequency band and applications, FS networks, and in particular high density FS

networks, are also likely to be deployed in the same population centres.

1602-10

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 10

pfd distributions at 30° elevation for GEO1 model

(6 co-frequency beams of 60 dBi)


Per

cen

t o

f o

ccu

ren

ce

Multibeam distribution

Single beam aggregate distribution


Correlation distribution of the two services may need to be taken into account when applying the

methodology.

5 Conclusion

This Annex proposes a statistical methodology for computing interference from satellites into FS

receivers. The methodology takes into account realistic satellite characteristics (such as maximum

power, number of beams, antenna gain and pattern and minimum pointing elevation angle). It

permits a detailed analysis of the impact of satellites on FS systems and could be used in sharing

studies pertaining to the assessment of pfd limits to be applied to satellite services to protect the FS

in a multi-satellite environment. On this basis, examples of calculations using this methodology are

given in Appendices 1-6 for the satellite models described in § 3:

– For GSO satellites (without operational elevation limit):

– model GEO1 (6 co-frequency beams with 60 dBi antenna gain), Appendix 1.

– For GSO satellites (with 15° operational elevation limit):

– model GEO1 (6 co-frequency beams with 60 dBi antenna gain), Appendix 2;

– model GEO2 (4 co-frequency beams with 55 dBi antenna gain), Appendix 3.

– For non-GSO satellites (with 20° operational elevation limit):

– model MEO1 (4 co-frequency beams with 50 dBi antenna gain), Appendix 4;

– model MEO2 (3 co-frequency beams with 45 dBi antenna gain), Appendix 5.

Finally, Appendix 6 provides an example of implementation of the statistical pfd levels obtained

with this methodology based on the case of non-GSO satellites.

1602-11

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 11

pfd distributions at 10° elevation for GEO1 model

(60 dBi multibeams)


Per

cen

t o

f o

ccu

ren

ce

Without elevation limitation

With 15° operational elevation limitation


Appendix 1

to Annex 1

1602-12

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 12

pfd distributions for GEO1 model (60 dBi multibeam) without operational

elevation limitation


Per

cen

t o

f o

ccu

ren

ce 0° e levation

5° e levation

10° elevation

15° elevation

20° elevation

25° elevation

30° elevation

35° elevation

40° elevation

45° elevation

50° elevation

60° elevation

70° elevation

80° elevation

90° elevation

1602-13

0 10 20 30 40 50 60 70 80 90

–104

–107

–110

–113

–116

–119

–122

–125

–128

–131

–134

–137

–140

–143

FIGURE 13

Aggregate pfd masks for GEO1 model (60 dBi multibeam) without operational elevation limitation


pfd

lev

el

(dB

(W/(

m2 ·

MH

z))

)

Regulatory mask

Maximum

99.9%

99.5%


Appendix 2

to Annex 1

1602-14

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 14

pfd distributions for GEO1 model (60 dBi multibeam)

with 15° operational elevation limitation


Per

cen

t o

f o

ccu

ren

ce 0° e levation

5° e levation

10° elevation

15° elevation

20° elevation

25° elevation

30° elevation

35° elevation

40° elevation

45° elevation

50° elevation

60° elevation

70° elevation

80° elevation

90° elevation

1602-15

0 10 20 30 40 50 60 70 80 90

–104

–107

–110

–113

–116

–119

–122

–125

–128

–131

–134

–137

–140

–143

FIGURE 15

Aggregate pfd masks for GEO1 model (60 dBi multibeam) with 15° operational elevation limitation


pfd

lev

els

(d

B(W

/(m

2 ·

MH

z))

)

Regulatory mask

Maximum

99.9%

99.5%


Appendix 3

to Annex 1

1602-16

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 16

pfd distributions for GEO2 model (55 dBi multibeam)



Per

cen

t o

f o

ccu

ren

ce 0° e levation

5° e levation

10° elevation

15° elevation

20° elevation

25° elevation

30° elevation

35° elevation

40° elevation

45° elevation

50° elevation

60° elevation

70° elevation

80° elevation

90° elevation

1602-17

0 10 20 30 40 50 60 70 80 90

–104

–107

–110

–113

–116

–119

–122

–125

–128

–131

–134

–137

–140

FIGURE 17



pfd

lev

els

(d

B(W

/(m

2 ·

MH

z))

)

Regulatory mask

Maximum

99.9%

99.5%


Appendix 4

to Annex 1

1602-18

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 18

pfd distributions for ME01 model (50 dBi multibeam)



Per

cen

t o

f o

ccu

ren

ce 0° e levation

5° e levation

10° elevation

15° elevation

20° elevation

25° elevation

30° elevation

35° elevation

40° elevation

45° elevation

50° elevation

60° elevation

70° elevation

80° elevation

90° elevation

1602-19

0 10 20 30 40 50 60 70 80 90

–104

–107

–110

–113

–116

–119

–122

–125

–128

–131

–134

–137

–140

–143

FIGURE 19



pfd

lev

els

(d

B(W

/(m

2 ·

MH

z))

)

Regulatory mask

Maximum

99.9%

99.5%


Appendix 5

to Annex 1

1602-20

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 20

pfd distributions for ME02 model (45 dBi multibeam)



Per

cen

t o

f o

ccu

ren

ce 0° e levation

5° e levation

10° elevation

15° elevation

20° elevation

25° elevation

30° elevation

35° elevation

40° elevation

45° elevation

50° elevation

60° elevation

70° elevation

80° elevation

90° elevation

1602-21

0 10 20 30 40 50 60 70 80 90

–104

–107

–110

–113

–116

–119

–122

–125

–128

–131

–134

–137

–140


pfd

lev

els

(d

B(W

/(m

2 ·

MH

z))

)

Regulatory mask

Maximum

99.9%

99.5%

FIGURE 21

Aggregate pfd masks for MEO2 model (45 dBi multibeam) with 20° operational elevation limitation


Appendix 6

to Annex 1

Example implementation of the methodology for non-GSO case

As described in § 2 of Annex 1, the calculations of interference from a non-GSO FSS system to an

FS station are typically presented as an I/N distribution, as the curves in Fig. 2.

The maximum short-term I/N scenarios represent the interference caused by a satellite passing

through the main beam of the considered FS station, under the assumption that this satellite

produces the maximum pfd level with regard to the pfd mask under consideration.

The examples in the Figures in Appendices 4 and 5 show, for all elevation angles, that the

occurrence of the maximum pfd scenario is small and that, in a large majority of the cases, the pfd

produced by the non-GSO satellite is below the pfd mask under consideration.

The combined effect of the low occurrence of the maximum pfd scenario and the lower pfd levels in

the large majority of the cases will tend to decrease the percentage related to the maximum I/N

distribution.

Acknowledging that the short-term part of the distribution is produced in the main beam of the FS

and hence is related to the same elevation with regard to the pfd value, the combined effect on the

tail of the distribution can be obtained by convolving the I/N distribution (for the low percentages)

with the corresponding pfd distribution for the considered FS elevation such as given on Fig. 22

(using the methodology described in this Recommendation).

1602-22

–159 –154 –149 –144 –139 –134 –129 –124 –119 –114 –109 –104

1

10

100

10–1

10–3

10–2

FIGURE 22

Typical pfd distribution produced by a non-GSO system


Per

cen

t o

f o

ccu

ren

ce


On this basis, Fig. 23 provides the convolved I/N result of this example compared with the I/N

derived from the pfd mask under consideration.

1602-23

5 1510 2520

1

10

100

10–1

10–3

10–2

10–4

10–5

FIGURE 23

Comparison of example maximum and convoluted interference distribution

I/N (dB)

Per

cen

t o

f o

ccu

ren

ce

Maximum I/N scenario

Convoluted I/N scenario

Criteria

Documents

RECOMMENDATION ITU-R SF.1602 - Methodology …...Recommendation ITU-R SF.1602 (02/2003) Methodology for determining power flux-density statistics for use in sharing studies between